The present invention relates to machine vision systems and more particularly to a system that uses an area scan camera to read identification codes on parts and to associate those codes with parts at specific locations on a conveyor.
Many different industries now use imaging systems to track locations of items (e.g., parts, packages, etc.) within a facility and more specifically on conveyors, transfer lines, etc. To track parts on a conveyor, bar or 2D matrix codes are applied to each part and a camera is provided adjacent the conveyor for sensing the code as the part passes through a field of view (FOV). In order to provide high resolution images with minimal hardware cost, most systems use a line camera to sense parts and codes. While line scan cameras work well in some applications, systems that use a line scan camera have several shortcomings.
First, line scan cameras are only capable of generating a single image of a part and associated code. In many cases when a single image is obtained, image quality of the single image may be insufficient for decoding purposes due to variations in code tilt angle within the FOV, jitter of the part or camera during image acquisition, imperfect lighting conditions, poor mark quality, etc., and therefore line scan cameras that only obtain a single image often have read rates which are unacceptable for some applications.
Second, while it may be relatively inexpensive to purchase a line scan camera, often times the process of properly setting up line scan systems to be accurately aligned relative to conveyor motion is time consuming and hence relatively expensive.
Other systems that include two dimensional area scan cameras have been configured that can read codes with much improved read rates due to the fact that area scan cameras are capable of obtaining multiple images of a code as the code passes through a FOV and therefore several decode attempts per code can be attempted using different images. While systems including area scan cameras have relatively high read rates, unfortunately known area scan systems cannot correctly associate decoded codes with precise conveyor locations.